Which one of the following could be true?

Ryan on September 17, 2019

Why is D correct? Why is E incorrect?


Create a free account to read and take part in forum discussions.

Already have an account? log in

Irina on September 17, 2019


This game requires us to determine the order of seven musicians - L M N O P S T. The following rules apply:

(1) L must perform earlier than N
L< N

We can infer that N cannot perform 1st, and L cannot perform 7th.

(2) M must perform earlier than T
We can infer that M cannot be 7th, and T cannot be 1st.

(3) There must be exactly one performance between O & L

L _ O or O_L

(4) There must be exactly one performance between M & P

M_P or P_M

(5) P must perform 1st or 7th.

P -1 v 7

So we can infer that M must perform 3 or 5 per rule (4).

Let's diagram all the rules together:

___ ___ ___ ___ ___ ___ __
1 2 3 4 5 6 7
/P /M /M /P
~N ~L

Let's look at the answer choices:

(A) M performs 4th.
Impossible. M must be 3d or 4th per rules (3) and (5).

(B) N performs 1st.
Impossible. N cannot be #1 per rule (1).

(C) O performs 5th.
Since L cannot be 7th, the only way O could be 5th is if L is 3d but then there is no place left for M with both 3d and 5th spot taken, hence this scenario is also impossible.

(D) S performs 7th.
If S performs 7th, P must be 1st, M must be 3d, Then L & O could be #2 and #4, and N & T #5 and #6. Since this scenario complies with all the rules, (D) is the correct answer.

1 2 3 4 5 6 7

(E) T performs 2d.

Impossible. If T performs 2d, M must perform 1st per rule (2) but per rules (4) (5), only one performance can separate M & P and P must be 1st or 7th. If M is #1, it will force P into #3 slot, which violates rule (5). We can thus conclude that T cannot be #2.

1 2 3 4 5 6 7

Let me know if this makes sense and if you have any further questions.